An excerpt from Understanding High-Risk Pregnancy: A Patient’s Guide to Prenatal Complications.

What is a high-risk pregnancy?

You may find it strange that there is no single accepted definition of what constitutes a high-risk pregnancy. Probably more than half of women will have at least one risk factor that could be an issue, but for most of these women it will minimally affect their pregnancy care or the outcome. For other women, their risk factor could seriously impact their health or the health of the baby. The focus should be on those risk factors and complications that can affect pregnancy outcomes, and how they are managed.

Who manages pregnancies with risk factors and complications?

Becoming a physician who cares for women during pregnancy requires many years of training. After college and medical school, a physician who desires to focus on the care of women and pregnancy will do a residency in obstetrics and gynecology. This is a four-year program of education and hands-on experience during which the physician receives training in routine gynecologic care, pregnancy and delivery management, infertility, and gynecologic cancers. At the conclusion of this residency, the physician is then eligible to become board-certified in obstetrics and gynecology and can practice independently. Board certification is granted by the American Board of Obstetrics and Gynecology (ABOG) after the physician successfully completes both written and oral examinations. These practitioners are referred to as obstetrics and gynecology generalists, and on occasion as obstetric generalists. Nurse midwives and family medicine physicians can also provide pregnancy care and do deliveries, but these practitioners primarily manage pregnant patients without significant risk factors.

Some physicians choose to perform further subspecialty training in management of pregnancy complications through a fellowship in maternal-fetal medicine (MFM). This additional three years of education and training focuses on managing pregnancy risk factors and more serious complications. Upon completing this fellowship, the physician is eligible to become additionally certified in the subspecialty of maternal-fetal medicine. This additional certification requires successful completion of both written and oral examinations administered by ABOG which are more focused on pregnancy complications.

Not all pregnancy risk factors require evaluation and care by an MFM subspecialist. Many are within the scope of expertise of obstetric generalists. On occasion a general obstetrician or a midwife will refer a patient to an MFM subspecialist for a consultation to assess the level of risk and create a plan of care, and the patient will then return to the referring provider for her ongoing prenatal care and delivery. Some MFM physicians only provide this type of consultative care and do not perform deliveries, while other MFM practices care for the patient during the entire pregnancy and postdelivery (postpartum) period.

Knowing the distinctions between these areas of maternal care can help you make a more informed decision about the medical professional you choose and entrust your care to during your pregnancy.

Medication use during pregnancy

It is common knowledge that the use of certain medications can have adverse effects on a pregnancy. The most well-known instance of this is thalidomide used in the 1950s and 1960s to treat morning sickness, which tragically caused severe limb deformities in some babies born to mothers who used it. Another example was the decades-long use of DES, a form of estrogen intended to prevent miscarriages. DES was linked to uterine birth defects and vaginal cancer years later in some women born to mothers who took it. Physicians have learned from these examples and are now more cautious about prescribing medication to pregnant women.

However, it is much easier to show that a drug causes harm than to prove with certainty that a medication is safe to take during pregnancy. Many drugs have been given to pregnant women for years without being linked to birth defects, and these are presumed to be safe. Examples of these are insulin and thyroid hormones. A few medications are associated with a very high risk of birth defects, such as retinoic acid (also known as Accutane), a derivative of vitamin A used for treating acne. There are medications associated with a lower risk (less than three percent) of causing birth defects which are still avoided if possible, such as certain anti-seizure medications. And then there is the largest group of medications where there is some level of uncertainty.

You and your provider should discuss medications you are currently taking, as well as those being prescribed during pregnancy so you can weigh the benefits versus the risks. Every obstetric provider discusses common medications multiple times every day, so do not shy away from asking. In some instances, a physician will still recommend a medication that has some known risk, but this is usually a situation where this is the best or only medication to treat the mother’s serious health condition and the risk of the medication causing an adverse effect on the fetus is relatively low. Examples of this might be warfarin (a blood thinner) for patients with a mechanical heart valve, and chemotherapy to treat cancer. But the most common situation is where there is significant experience over many years with use of a medication during pregnancy with no apparent increase in adverse effects on the fetus. Even without randomized controlled trials that prove that they are safe, these medications are presumed to be acceptable for use in pregnancy as long as there is an appropriate indication. The list of these medications presumed to be safe include acetaminophen (Tylenol) and many cold remedies, but also many drugs used to treat other medical conditions. The discussion will often come down to the benefits of the medicines far outweighing any theoretical but unseen risks that might remain, and you should feel comfortable taking them.

One of the many changes to your body during pregnancy is an increase in the amount of circulating blood. Maternal blood volume can increase fifty percent by the third trimester compared with pre-pregnancy, and even more in twin pregnancies. This increased blood volume delivers the extra nutrients and oxygen required by the developing fetus, and it allows the mother to tolerate the normal bleeding that occurs during and after delivery. With this increased blood volume, doses of medication may need to be adjusted as pregnancy advances to maintain a steady blood level.

With more attention to mental health today, more women of reproductive age are being treated with medications for depression and anxiety. Concerns have been raised with a few of these drugs when taken during pregnancy, but for most medications the concerns have not been consistent or conclusive. Some women will choose to stop their medication during pregnancy, while others feel it is vital to their ability to function. If you currently take medication for any mental health issue, ensure your care provider addresses your needs and supports the continuation of your medications if warranted.

Concern about the development of postpartum depression (PPD) is also appropriate. Patients with a history of depression or an anxiety disorder are known to be at increased risk for developing PPD. Sertraline (Zoloft) is a medication used for depression and anxiety disorders that many physicians are most comfortable with during pregnancy and breastfeeding. It has a track record of use now for many years and by thousands of patients without evidence of adverse effects. Even for patients not on it during pregnancy, it may be recommended that medication be started during pregnancy if depression symptoms warrant it. It may also be reasonable to start it a month or so before anticipated delivery for those at risk of PPD, as it often takes a few weeks to see beneficial effects.

Ultrasound

The introduction of ultrasound examinations into routine clinical practice in the 1980s revolutionized obstetric care. The field of obstetrics transformed from caring for one patient (only the mother) to caring for two. Before routine ultrasound use, birth defects were rarely identified before birth, and the presence of twins was frequently unknown until delivery. In the United States and many other countries today, almost all women have at least one ultrasound during pregnancy, and most have more than one.

Ultrasound can assess fetal structure and function. It can identify organs that do not appear to have developed normally and those not doing what they are supposed to do. It can see a heart which is not pumping blood very well, an abnormal growth of tissue in the lungs, kidneys that are not making urine, legs that are not moving, and growth that is lagging.

Ultrasound is an amazing tool that continues to improve with advances in technology. All evidence suggests that it is safe to use and does not harm the fetus, but it should only be used when there is a medical indication. For the high-risk conditions described in this book, ultrasound can be an essential tool in pregnancy management, and can be used as often as needed without concerns for adverse effects.

Alan M. Peaceman is an obstetrician-gynecologist.